Voltage regulating apparatus



1961 J. G. SOLA 2,996,656

VOLTAGE REGULATING APPARATUS Filed Feb. 2. 1959 24a lmlllm m IN VEN TOR.

wa /J Kg g1 way United States Patent 2,996,656 VOLTAGE REGULATING APPARATUS Joseph G. Sola, River Forest, Ill., assignor to Basic Products Corporation, Village of West Milwaukee, Wis., a corporation of Wisconsin Filed Feb. 2, 1959, Ser. No. 790,428 11 Claims. (Cl. 323-45) This invention relates to voltage regulating apparatus and more particularly to a voltage regulating system comprising a high reactance transformer and one or more capacitors for regulating voltage to a load irrespective of load variations over a certain range thereof and irrespective of line supply voltage variations over a certain range thereof, and it is an object of the invention to provide improved apparatus of this character.

It is a further object of the invention to provide improved apparatus of the character indicated for supplying a constant voltage to a load under the conditions stated.

Constant voltage devices are known according to the patent, No. 2,143,745, to the same inventor as the subject application and the present invention is an improvement thereover. Devices according to the prior patent have served and continue to serve satisfactorily a .wide variety of load and line supply voltage conditions. However, there recently has appeared a need for a voltage regulating and more particularly a constant voltage apparatus to supply loads requiring very high currents relative to the voltage, 'these loads having to be supplied with a constant or regulated voltage even though the load may vary from no load to full load and even though the line supply voltage may vary over a rather wide range. The indicated need has not been completely satisfied by devices according to the prior patent, and it is therefore a further object of the invention to provide improved devices which will satisfy it.

The basic problem with which the subject invention is concerned is one .of long standing. It is the problem of providing a constant or regulated voltage to a load from a particular source apparatus. There are two aspects to the problem, maintaining a constant voltage to a load when the line supply voltage varies, and maintaining a constant voltage at that load when the load current varies. The first of these aspects has been substantially solved by the patent, No. 2,143,745, already referred to. In this patent a constant voltage transformer is disclosed which utilizes a secondary winding to which a capacitor is connected for providing a high degree of saturation in the core of the transformer associated with that winding, together with a compensating winding which is closely coupled with the primary winding to produce a constant voltage across a load for the voltages and currents ordinarily employed. Even in circuits wherein such a constant voltage transformer supplies a load through a rectifier and afilter, the regulation at the load has been enabled to be achieved for the rated range of variation of primary voltages in cases wherein the output voltages were high relative to the load currents required, and a certain degree of regulation has been obtained for variations in load current. In such well known apparatus the voltage drops occurring through the rectifier, filter and the various transformer windings due to current flow have been negligible compared to the output voltage.

However, in apparatus wherein it is desired to maintain a constant :or regulated voltage across a load, for example, a DC. load wherein the currents required are very high compared to the voltage across the load, the problem of maintaining a constant or regulated voltage across the load becomes considerably more diificult. This is due to the fact that the resistances of the filter,

"ice

2 the rectifier, the leads, the windings, etc., cause voltage drops due to current flow which are a much greater percentage of the output voltage available. I

It is an object of the invention to provide improved apparatus of the character indicated for supplying a load, particularly a DC. load, requiring high currents relative to voltage with substantially constant voltage over rated ranges of variations in supply voltage and load current.

It is a further object of the invention to provide improved devices of the character indicated which are small in size and economical of iron and copper.

Further objects of the invention will become apparent as the description proceeds.

In carrying out the invention in one form, apparatus for supplying a regulated voltage to a load which may be variable over a certain range from a source of alternating voltage which also may be variable over a certain range is provided comprising a core, primary winding disposed on said core and adapted to be supplied from said source with an alternating voltage of predetermined nominal value and frequency, a first secondary winding disposed on said core on one side of said primary winding, a first high reluctance magnetic shunt disposed between said primary winding and said first secondary winding, a capacitor connected across said first secondary winding, said capacitor having a capacity value which when taken in combination with said first secondary winding effects under operating conditions a flux density in the core interiorly of said first secondary winding substantially greater than the flux density in the core interiorly of said primary winding and sufiicient to produce a condition of substantial saturation in said first secondary winding core portion, a regulating secondary winding disposed on the other side of said primary winding, a second high reluctance magnetic shunt disposed between said primary winding and said regulating secondary winding, and means deriving a voltage from said first secondary winding, said voltage deriving means and said regulating secondary winding being connected in series voltage bucking relationship and being adapted to be connected to a load.

For a more complete understanding of the invention, reference should be had to the accompanying drawing, in which:

FIGURE 1 is a plan view, partially in section, of one form of transformer which may be utilized in carrying out the invention; and

FIG. 2 is a circuit diagram showing the electrical connections of the transformer of FIG. 1, together with other circuit components forming one embodiment of the invention.

' Referring to the drawing, a transformer 10 is shown, including a primary winding 11, a secondary winding 12, a winding 13 closely coupled to secondary winding 12, a secondary winding 14, a winding 15 closely coupled to secondary winding 14, and an iron core 16.

The core 16 is shown as being of the shell type having a central leg 17 and an outer'shell consisting of side legs 18 and '19 and end legs 21 and 22. As shown, the core is formed of the desired stack height from a series of E and I laminations laid together in lap joints for good magnetic circuitry. This is of course exemplary and other forms of cores may be used, such for example as cores wherein the central leg 17 is punched from an integrally formed outer lamination.

The windings 11, 12, 13, 14 and 15 may, of course, be form-wound and appropriately disposed on the central leg 17 during the assembly process.

Disposed between the primary winding 11. and secondary winding lz'there is a high reluctance magnetic shunt consisting of iron portions 23 and 24, together with air or other nonmagnetic gaps 23a, 23b and 24a and 24b, respectively. Similarly, between primary winding 11 and secondary Winding 14 there is a high reluctance magnetic shunt consisting of iron portions 25 and 26 and air or other nonmagnetic gaps 25a and 25b and 26a and 26b, respectively.

The high reluctance shunts 23, 23a, 23b and 24, 24a, 2417 between the primary winding 11 and the secondary winding 12 provide a leakage flux path whereby a certain portion of the iluxes of each of these two windings may link the particular winding to the exclusion of the other. Similarly, the high reluctance shunts 25, 25a, 25b and 26, 26a, 26b provide a leakage path between the primary winding 11 and the secondary winding 14 whereby a certain portion of the fluxes of each of these windings may link the particular winding to the exclusion of the other. In this manner, the core provides a high leakage reactance for each of the primary windings and secondary windings. Other well-known constructions for obtaining a leakage flux path may of course be used.

It is necessary that the flux generated by the secondary winding 12 and linking itself does not link the secondary winding 14 which performs a regulating function and must be independent of the secondary Winding 12. This is achieved, according to the subject invention, by disposing the secondary winding 14 on the opposite side of the primary winding 11, compared to the secondary winding 12 and by disposing the high reluctance shunts 25, 25a, 25b and 26, 26a, 26b between the primary winding 11 and the secondary winding 14.

The secondary winding 13 forms a load secondary winding and is closely coupled to the secondary winding 12. Since one principal embodiment of the subject invention is that form providing a DC. load with relatively high currents compared to to voltage, it is desired that there be a minimum amount of resistance in the windings supplying the load. For this reason the secondary winding 13 is wound adjacent the central leg of the core 17 and is interiorly disposed of the secondary winding 12. Thus the length of the winding 13 is reduced and its resistance is therefore maintained at a minimum.

The secondary winding is a regulating winding and is closely coupled to the secondary winding 14, and thereby reflect's the flux condition existing in the secondary winding 14.

The secondary winding 15 also is wound adjacent the central leg 17 of the core interiorly of the winding 14 to maintain its resistance as low as possible. As will be subsequently explained in this specification, the secondary winding 15 performs its regulating function essentially independently of the voltage variations occurring in the primary winding 11. and also independently of the flux conditions existing With respect to the secondary winding 12.

Suitable insulation between the various windings themselves and between them and the transformer core is of course provided, and, by way of example, insulating pieces 27, 28 and 29 are shown between the primary winding 11, the secondary winding 13 and the secondary winding 15, respectively, and the central leg of the core 17.

For a further description of the structure of the invention and for an understanding of the operation thereof, reference should be had to FIG. 2 which is a circuit diagram showing the connections for the various components. In this figure, the reference characters are the same as those used in FIG. 1 to designate corresponding parts. The core 16 and the high reluctance shunts 23, 24 and 25', 26 together with their air gaps are shown schematically and the secondary windings 12 and 14 are shown disposed on opposite sides of the primary winding 1:1 with the shunts in between. The primary winding 11 is shown connectible to a source S of alternating current having a predetermined nominal voltage 4 l and frequency such for example as volts at 60 cycles.

Connected across secondary winding 12 is a capacitor 31 which is related to the secondary winding 12 in such a manner as to produce a very high flux density or saturation in the portion A of the central leg 17 of the core immediately underneath the secondary winding 12. In one typical form of apparatus, the flux density in this portion of the core was of the order of 127,500 lines per square inch when the flux density in the portion B of the central leg 17 of the core immediately underneath the primary winding 11 was of the order of 98,000 lines per square inch, assuming a stacking factor of unity. The high flux density in the portion A of the central leg 17 is brought about by the phenomena of ferro-resonance which can occur in the apparatus as shown at appropriate voltages because the high reluctance shunts 23, 23a, 23b, 24, 24a and 24b enable the flux generated by the secondary winding 12 to link itself to the exclusion of the primary winding 11. By virtue of the saturation conditions existing in the secondary core portion A caused by the ferro-resonant phenomena, the voltage across the secondary winding 12 and consequently the voltage across the secondary winding 13 are substantially independent of variations in the voltage across the primary winding 11. The portion of the device thus far described relative to the primary winding 11, secondary windings 12 and 13 and the associated core portions form essentially a constant voltage device similar to that described in Patent No. 2,143,745.

Connected across the secondary winding 14 is a capacitor 32 which is related to the secondary winding 14 so as to produce a flux density in the portion C of the central leg 17 of the core immediately underneath the secondary winding 14 which is equal to or greater than the flux density associated with the primary portion B of the central leg 17, also due to ferro-resonant phenomena. It will be understood that because of the presence of the shunts 25, 25a, 25b and 26, 26a, 26b the flux density existing in the portion C of the central leg 17 may be less than the flux density in the portion B of the central leg 17 of the core 11 in the absence of the capacitor 32. Thus the presence of the capacitor 32 increases the flux density in the portion C of the central leg 17 to a value as desired in particular devices, as will subsequently become clear in this specification. The secondary winding 15 being closely coupled to the secondary winding 14 reflects the flux condition therein and provides a regulating voltage in the circuit supplying the load as will be subsequently described.

The presence of the high reluctance shunts 25, 25a,

25b and 26, 26a, 26b alone or in combination with the saturation condition which may be produced by the combination of capacitor 32' and secondarywinding 14, enables the secondary winding 14 and the closely coupled winding 15 to be substantially independent of voltage variations in the primary winding 11. Moreover, the load supplied by the series combination of secondary windings 13 and 15 may be supplied with a regulated or a constant voltage irrespective of variations in current supplied to such load as will be subsequently described. The voltage across such load will also, according to the invention, be independent of voltage variations in the source of supply connected to the primary winding 11 over the rated range.

The secondary winding 14 and the connected capacitor 32, while similar in circuitry to the secondary winding 12 and its connected capacitor 31, perform a substantially different function. The winding 15 provides a regulating component voltage which when vectorially added to the voltage component of winding 13 provides a substantially constant voltage, for example, across the load 33 irrespective of variations in the supply to the primary winding 11 and irrespective of variations in the load 33 from no load to full load. The windings 13 and 15 are connected in series with each other by means of the conductor 34, and the extremities of the windings 13 and 15 are connected to a bridge rectifier 35 through conductors 36 and 37 at terminals 39 and '40, respectively.

In one particular form of the invention which was actually constructed and operated, the load 33 was a pure resistance load supplied from the rectifier bridge 35 through a filter 3 8. The load 33, the filter 38, and the rectifier bridge 35 may, of course, be considered as a load supplied from the windings 13 and 15 through conductors 36 and 37. Thus while the load in the particular example described is a DC. load, it will be understood that the windings 13 and 15 may supply an A.C. load and suitable regulation characteristics according to the invention may be provided. The rectifier bridge 35 is a full wave rectifier and, for example, consists of four rectifier units appropriately connected, which units may be of the germanium type, the four rectifier units being designated as 41, 42, 43 and 44. The output of the rectifier appears at the terminals 45 and 46 and is supplied by means of the conductors 47 and 48 to the filter 38.

The filter 38 may consist, as shown, of two capacitors 49 and 51, between which is interposed an inductor or choke 52. At the exit of the filter 38 there is a bleed resistor 53 for a purpose to be described and from the bleed resistor 53 the conductors 54 and 55 extend to the load 33, the load terminals being 56 and 57.

The particular example of device which was actually constructed and operated, provided to the load 33 currents varying from zero to 40 amperes while the voltage across the load terminals 56 and 57 remained at volts. In the same setup, the voltage across the load 33 did not vary more than one percent for a permissible variation in the primary voltage from 95 volts to 125 volts. The capacitors 49 and 51 in the said practical example each consisted of four units of 35,000 microfarads each and the choke coil 52 consisted of 24 turns of No. 5 square copper wire. The high microfarad values of capacitors 49 and 51 provide an elfective filter for any ripple components in the output voltage and, in addition, enables the provision of a substantially square wave input to the rectifier terminals 39 and 40 whereby the rectifier operates at a high e-fiiciency. Any remaining ripple components in the rectifier output voltage are effectively eliminated by the choke coil 52. It was actually observed in the example being described by means of an oscilloscope that the voltage input at the terminals 39 and 40 of the rectifier was substantially a square wave when the load 33 was zero. However, when the load 33 was at its full value, a substantial ripple component could be observed in the voltage input at terminals 39 and 40, which ripple did not appear at terminals 56 and 57.

It is of course understood that in devices intended to supply low voltage to a load such, for example, as 10 volts which exist across the terminals 56 and 57, it is necessary that the resistance drops in the circuit components be reduced to as small a value as possible. Thus the large size of wire is used for the choke 52 and germanium or similar units may be used in the rectifier. The voltage drop across each of the rectifier units 41, 42, 43 and 44 was in the order of eight-tenths of a volt per unit.

The function of the bleeder resistor 53 is to cause a continuous load current through the rectifier even though the current going through load '33 may be zero. In this manner the rectifier is operating on the most linear portion of its characteristic. There is a drop in voltage across the rectifier units whenever there is current flowing, and even though it tends to be constant over a certain current range it nevertheless increases, and likewise there is an increase in voltage drop across filter choke 52 whenever the current therethrough increases, and

6 there are of course voltage drops in the various leads including the windings 13 and '15. For a constant voltage to be maintained across the terminals 56 and 57 for variations in load from no load to full load, it is necessary that the transformer 16 with its various windings and capacitors provide for a voltage characteristic which will achieve this desirable end. Inasmuch as an increase in current causes an increase in voltage drop throughout these components as described, it is necessary that the transformer windings 13 and 15 together provide a rising voltage with increasing load cur-rents through the load 33.

In the actual examplebeing described, the voltage across winding 13 at no load was 14 volts when the primary Winding was connected to a source of supply of volts at 60cycles. At a full load of 36 amperes DC. in load 33, the voltage across winding 13 was 12.8 volts. Under similar conditions at no load, the voltage across the regulating winding 15 was 4 volts and at full load the voltage across the regulating winding was 4.43 volts. In the said particular device, the voltage of winding 15 was connected in bucking relationship to the voltage of winding 13 in the circuit supplying the load. Consequently, the voltage across the combination of windings 13 and 15, that is, across the conductors 36 and 37 at no load was 10 volts and across the same conductors at full load was 10.75 volts, or an increase of about 7.5 percent. This increase in voltage compensated for the voltage drops through the rectifier, the filter and leads so that the voltage across the terminals 56 and 57 at no load was 10 volts and at full load was also 10 volts.

In the said particular example, the various constructional features of the transformer 10 including the core 16 and the various windings may now be given for a full understanding of the invention. The primary winding 11 consisted of turns of #14 copper wire, the secondary winding 12 consisted of 480 turns of #116 copper wire, the secondary winding 13 consisted of 12 turns of double #6 square copper wire, the secondary winding .14 consisted of 460 turns of #20 copper wire, and the secondary winding 15 consisted of 4 turns of double #7 square copper wire. The capacitor 31 was of 10 microfarads and the capacitor 32 was of 2.25 microfarads. The core 16 consisted of a stack 2 7 inches in height of transformer steel 26 gauge designated as M22 cold reduced by the manufacturer thereof. The exterior dimensions of the core along the sides 18 and 19 were 7% inches whereas the length along the ends 21 and 22 was 5% inches. The width of the central leg 17 was 1% inches whereas the width of the outside legs 18 and 19 and the width of the end legs 21 and 22 was /s of an inch. The shunt members 23, 24, .25 and 26 were of the same height as the thickness of the stack and each had a width of A; of an inch. The length of the shunts 23 and 24 was such as to provide an air gap 23a, 23b, and an air gap 24a, 241) each totaling .039 inch, and the length of the shunts 25 and 26 was such as to provide an air gap 25a, 25b and an air gap 26a, 26b each totaling .050 inch. The filter choke had a nonmagnetic gap in the magnetic circuit of .030 inch filled with insulating fiber.

With the various constants of the device given it was found under no load conditions, that is, no current flowing across terminals 5'6 and 57, but with 110 volts at 60 cycles supplied to the primary winding 11, the voltage across capacitor 31, that is across the winding 12, was 576 volts, which dropped to '525 volts at full load. Under these same conditions, the voltage across capacitor 32, that is to say across winding 1'4, was 460 volts at no load and this increased to 525 volts at full load.

As has already been pointed out, when the device as thus far described is in operation the voltage across the regulating winding 15, although bucking the voltage across the secondary winding 13, increases in magnitude as the load current at terminals 56 and 57 increases from no load toward full load. The voltage across winding 14 and of course the fiux density in the core associated with this winding also increases from no load to full load. At full load the flux density in the portion C of the central leg 17 of the core was of the order of 107,000 lines per square inch.

As has been indicated, the rated range of primary voltage variation of the device made and tested was from 95 volts to 125 volts. At 95 volts across the primary 11 for no load the voltage existing across terminals 56 and 57 was 10.10 volts and at full load this same voltage was 9.95 volts or a decrease of about 1 /2 percent. At 125 volts across the primary winding, the voltage across terminals 56 and 57 was 10.05 volts and at full load this same voltage was 9.90 volts or a decrease of about 1 /2 percent. Thus, it is seen that the example described has a maximum regulation of 1% percent at the extremes of the permissible range of primary voltage variation and for the nominal value of 110 volts there was no variation.

One characteristic of the device as has already been described is that the voltage across the regulating winding 15 increases with increasing load current. The voltage across the winding 13 decreases with increases in load current, yet the resultant voltage of the windings 13 and 15 connected in bucking relationship rises in sufficient amount to compensate for the voltage drops through the rectifier, filter, circuits and leads, etc.

As an explanation of this phenomena, it is suggested that the voltage vectors of the windings 13 and 15 shift relative to each other with difierent load currents so that the combination of the two vectors results in the voltage increase desired. The phase shift in these two voltages is enabled to take place because of the fact that the windings 12 and 14 are isolated from each other and from the primary winding due to the high reluctance shunts 23, 24 and 25, 26. It is also a theory of operation that the winding 15 is inductive, even though coupled to the winding 14 across which a capacitor 32 is connected, relative to the winding 13 which supplies the principal component of the load voltage, and thus when leading current from winding 13 is flowing through the inductive winding 15 a voltage rise is produced. It has also been found under load conditions that a voltage rise will still be produced across the winding 15 even though the capacitor 32 is disconnected from the winding 14, and the device will produce a substantial degree of regulation although not as satisfactory as that produced when the capacitor 32 is present. For A.C. load, that is, for loads connected directly across the conductors 36 and 37 and with the elimination of the rectifier system 35, etc., good voltage and current regulation are achieved without the presence of the capacitor 32.

A balance must be achieved between the various components of the circuit, namely, the number of turns in the windings, the dimensions of the air gaps, the microfarad values of the capacitors and the dimensions of the iron core. To produce the desired result in a device intended for a different load, variations may be selected in each of the components indicated. Irrespective of what changes are selected in these components, it is however essential that the regulating winding 15 and the winding 14 to which it is coupled, be on the opposite side of the primary winding from the secondary winding 12 and moreover be separated from the primary winding by a shunt such as high reluctance shunts 25 and 26 and the associated air gaps. This is in order that the winding 15 and the winding 14 may act independently of the primary winding 11 depending upon the degree of saturation or ferro-resonance existing in the circuit defined by the winding 14 and capacitor 32. For some constructions it may be feasible to eliminate the capacitor 32 and the connected winding 1.4. Under these conditions the flux density in section C of the central leg of the core will, of course, be less than that in section B, since some flux will be diverted through the shunts.

It will also be understood that the windings 13 and 15 are not essential as such but a certain number of turns may be tapped from winding 12 in place of winding 13 and a certain number of turns may be tapped from winding 14 in place of winding 15. The number oftapped turns from winding 12 and from winding 14 will then be connected in series to supply the load. A tap 58 and a tap 59 are shown on windings 13 and 15, respectively, for adjustment purposes.

While particular embodiments of the invention have been shown, it will be understood, of course, that the invention is not limited thereto since many modifications may be made, and it is, therefore, contemplated by the appended claims to cover any such modifications as fall within the true spirit and scope of the invention.

The invention having thus been described, what is claimed and desired to be secured by Letters Patent is:

1. Apparatus for supplying a regulated voltage to a load which may be variable over a certain range from a source of alternating voltage which also may be variable over a certain range comprising a core, a primary winding disposed on said core and adapted to be supplied from said source with an alternating voltage of predetermined nominal value and frequency, a first secondary winding disposed on said core on one side of said primary winding, a first high reluctance magnetic shunt disposed between said primary winding and said first secondary winding, a capacitor connected across said first secondary winding, said capacitor having a capacity value which when taken in combination with said first secondary winding efi'ects under operating conditions a flux density in the core associated with said first secondary winding substantially greater than the flux density in the core associated with said primary winding and sufiicient to produce a condition of substantial saturation in said first secondary winding core portion, a regulating secondary winding disposed on the other side of said primary winding, a second high reluctance magnetic shunt disposed between said primary winding and said regulating secondary winding, and means deriving a voltage from said first sec ondary winding, said voltage deriving means and said regulating secondary winding being connected in series voltage bucking relationship and being adapted to be connected to a load.

2. Apparatus for supplying a regulated voltage to a load which may be variable over a certain range from a source of alternating voltage which also may be variable over a certain range comprising a core, a primary winding disposed on said core and adapted to be supplied from such source with an alternating voltage of predetermined nominal voltage and frequency, a first secondary winding disposed on said core along one side of said primary winding, a first high reluctance magnetic shunt disposed between said primary winding and said first secondary winding, a capacitor connected across said first secondary winding, said capacitor having a capacity value which when taken in combination with said first secondary winding effects under operating conditions a flux density in the core associated with said first secondary winding substantially greater than the flux density in the core associated with said primary winding and suflicient to produce a condition of substantial saturation in said first secondary Winding core portion, a second secondary winding disposed on said core on the other side of said primary winding, a second high reluctance magnetic shunt disposed between said primary winding and said second secondary winding, first means deriving a load voltage from said first secondary winding, and second means deriving a regulating voltage from said second secondary winding, said first and second means being connected in series for supplying a load.

3. Apparatus for supplying a regulated voltage to a load which may be variable over a certain range from a source of alternating voltage which also may be variable over a certain range comprising a core, a primary winding disposed on said core and adapted to be supplied from such source with an alternating voltage of predetermined nominal voltage and frequency, a first secondary winding disposed on said core along one side of said primary winding, a first high reluctance magnetic shunt disposed between said primary winding and said first secondary winding, a capacitor connected across said first secondary winding, said capacitor having a capacity value which when taken in combination with said first secondary winding efiects under operating conditions a flux density in the core associated with said first secondary winding substantially greater than the flux density in the core associated with said primary winding and sufficient to produce a condition of substantial saturation in said first secondary winding core portion, a second secondary Winding disposed on said core on the other side of said primary winding, a second high reluctance magnetic shunt disposed between said primary winding and said second secondary winding, first means deriving a voltage from said first secondary winding, and second means deriving a voltage from said second secondary winding, said first and second means being connected in series and the voltage of said second means bucking the voltage of said first means for supplying a load.

4. Apparatus for supplying a regulated voltage to a load which may be variable over a certain range from a source of alternating voltage which also may be variable over a certain range comprising a core, a primary winding disposed on said core and adapted to be supplied from such source with an alternating voltage of predetermined nominal value and frequency, a first secondary winding disposed on said core on one side of said primary winding, a first high reluctance magnetic shunt disposed between said primary winding and said first secondary winding, a first capacitor connected across said first secondary winding, said first capacitor having a capacity value which when taken in combination with said load secondary winding efiects under operating conditions a flux density in the core associated with said first secondary winding substantially greater than the flux density in the core associated with said primary winding and sufficient to produce a condition of substantial saturation in said first secondary winding core portion, a second secondary winding disposed on said core on the other side of said primary winding, a second high reluctance magnetic shunt disposed between said primary winding and said second secondary winding, a second capacitor connected across said second secondary win'ding, said second capacitor having a value which when taken in combination with said second secondary winding effects under operating conditions a flux density in the core associated with said second secondary winding substantially greater than the flux density in the said primary core ,portion, first means deriving a voltage from said first secondary winding, and second means deriving a voltage trom said second secondary winding said first and second means being connected in series and the voltage of said second means bucking the voltage of said first means for supplying a load. 7 V

Apparatus for supplying a regulated voltage to a load which may be variable over a certain range from a source of alternating voltage which also may be variable over a-certain range comprising a core, a primary winding disposed on said core and adapted to be supplied from such source with an alternating voltage of predetermined nominal voltage and frequency, a first secondary winding disposed on said core along one side of said primary winding, a first high reluctance magnetic shunt disposed between said primary winding and said first secondary winding, a first capacitor connected across said first secondary winding, said first capacitor having a capacity value which when taken in combination with said load secondary winding effects under operating conditions a flux density in the core associated with said first secondary winding substantially greater than the flux density in the core associated with said primary winding and suificient to produce a condition of substantial saturation in said first secondary winding co're portion, a second secondary winding disposed on said core on the other side of said primary winding, a second high reluctance magnetic shunt disposed between said primary winding and said second secondary winding, a second capacitor connected across said second secondary winding, said second capacitor having a value which when taken in combination with said second secondary winding efieots under operating conditions a flux density in the core associated with said second secondary winding substantially greater than the flux density in the said secondary winding core portion as compared with the flux density therein in the absence of said second capacitor, first means deriving a voltage from said first secondary winding, and second means deriving a voltage from said second secondary winding, said first and second means being connected in series and the voltage of said second means bucking the voltage of said first means for supplying a load.

6. Apparatus for supplying a substantially constant voltage to a load which may be variable over a certain range from a source of alternting voltage which also may be variable over a certain range comprising a core, a pri mary winding disposed on said core and adapted to be supplied from such source with an alternating voltage of predetermined nominal voltage and frequency, a first secondary winding disposed on said core along one side of said primary winding, a first high reluctance magnetic shunt disposed between said primary winding and said first secondary winding, a capacitor connected across said first secondary winding, said capacitor having a capacity value when taken in combination with said first secondary winding effects under operating conditions a fiux density in the core associated with said first secondary winding substantially greater than the fiux density in the core associated with said primary winding and sufiicient to produce a condition of substantial saturation in said first secondary winding core portion, a second secondary winding disposed on said core on the other side of said primary winding, a second high reluctance magnetic shunt disposed between said primary winding and said second secondary winding, a load winding coupled to said first secondary winding, and a compensating winding coupled to said second secondary winding and connected in series with said load winding, the series combination of said load and compensating windings being adapted to be connected to a load.

7. Apparatus for supplying a substantially constant voltage to a load which may be variable over a certain range from a source of alternating voltage which also may be variable over a certain range comprising a core, a primary winding disposed on said core and adapted to be supplied from such source with an alternating voltage of predetermined nominal voltage and frequency, a first secondary winding disposed on said core along one side of said primary winding, a first high reluctance magnetic shunt disposed between said primary winding and said first secondary winding, a capacitor connected across said first secondary winding, said capacitor having a capacity value which when taken in combination with said first secondary winding efiects under operating conditions a flux density in the core associated with said first secondary winding substantially greater than the flux density in the core associated with said primary winding and sufiicient to produce a condition of substantial saturation in said first secondary winding core portion, a second secondary winding disposed on said core on the other side of said primary winding, a second high reluctance magnetic shunt disposed between said primary winding and said second secondary winding, a load winding coupled to said first secondary winding, and a compensating winding coupled to said second secondary winding and connected in series voltage bucking relationship with said load winding, the series compensation of said '11 load and compensating windings being adapted to be connected to a load.

8. Apparatus for supplying a substantially constant voltage to a load which may be variable over a certain range from a source of alternating voltage which also may be variable over a certain range comprising a core, a primary winding disposed on said core and adapted to be supplied from said source with an alternating voltage of predetermined nominal value and frequency, a first secondary winding disposed on said core on one side of said primary winding, a first high reluctance magnetic shunt disposed between said,primary winding and said first secondary winding, a first capacitor connected across said first secondary winding, said first capacitor having a capacity value which when taken in combination with said first secondary winding effects under operating conditions a flux density in the core associated with said first secondary winding substantially greater than the fiux den sity in the core associated with said primary winding and sufiicient to produce a condition of substantial saturation in said first secondary winding core portion, a second secondary winding disposed on said core on the other side of said primary winding, a second high reluctance magnetic shunt disposed between said primary winding and said second secondary winding, a second capacitor connected across said second secondary winding, said second capacitor having a value which when taken in combination with said second secondary winding effects under operating conditions a flux density in the core associated with said second secondary winding substantially greater than the flux density in the said primary core portion, a load winding coupled to said first secondary winding, and a compensating winding coupled to said second secondary winding and connected in series voltage bucking relationship with said load winding, the series combination of said load and compensating windings being adapted to be connected to a load.

9. Apparatus for supplying a substantially constant voltage to a load which may be variable over a certain range from a source of alternating voltage which also may be variable over a certain range comprising a core having a central leg and two outer legs, a primary winding disposed on said central leg and adapted to be supplied from said source with an alternating voltage of predetermined nominal value and frequency, a first secondary winding disposed on said central leg on one side of said primary winding, a first high reluctance magnetic shunt disposed between said primary winding and said first secondary winding, a first capacitor connected across said first secondary winding, said first capacitor having a capacity value which when taken in combination with said first secondary winding effects under operating conditions a flux density in the core associated with said first secondary winding substantially greater than the flux density in the core portion associated with said primary winding and sufiicient to produce a condition of substantial saturation in said first secondary winding core portion, a second secondary winding disposed on said central leg on the other side of said primary winding, a second high reluctance magnetic shunt disposed between said primary winding and said second secondary winding, a second capacitor connected across said second secondary winding, said second capacitor having a value which when taken in combination with said second secondary winding effects under operating conditions a flux density in the core associated with said second secondary winding substantially greater than the fiux density in the said primary core portion, a load winding coupled to said first secondary winding, and a compensating winding coupled to said second secondary winding and connected in series voltage bucking relationship with said load winding, the series combination of said load and compensating windings being adapted to be connected to a load.

10. Apparatus for supplying a regulated voltage to a load which may be variable over a certain range from a source of alternating voltage which also may be variable over a certain range comprising first and second transformer means excitable from said source with an -alter nating voltage of predetermined nominal value and frequency, said first and second transformer means each including core means, a secondary winding and voltage phase shifting means, said secondary windings being connected in series for supplying such load and each of said voltage phase shifting means comprising a winding closely coupled to the respective one of said secondary windings and a capacitor connected thereacross, and each of said phase shifting means having a relationship between the closely coupled winding and capacitor thereof so as to produce under operating conditions an increased flux density in the core portion associated therewith relative to the excitation flux density thereof.

11. Apparatus for supplying a regulated voltage to a load which may be variable over a certain range from a source of alternating voltage which also may be variable over a certain range comprising load and regulating transformer means excitable from said source with an alter nating voltage of predetermined nominal value and frequency, said load and regulating transformer means each including core means, a secondary winding and voltage phase shifting means, said secondary windings being connected in series bucking relationship for supplying such load and each of said voltage phase shifting means comprising a winding closely coupled to the respective one of said secondary windings and a capacitor connected thereacross, the phase shifting means associated with said load transformer means having a relationship between the closely coupled winding and capacitor thereof so as to produce under operating conditions a flux density in the core portion associated therewith substantially greater than excitation flux density thereof and suificient to produce a condition of substantial saturation in said core portion and the phase shifting means associated with said regulating transformer means having a relationship between the closely coupled winding and capacitor thereof so as to produce under operating conditions a flux density in the core portion associated therewith greater than the excitation flux density thereof.

Sola Jan. 10, 1939 Sola Jan. 20, 1959 

